Troubleshooting System Email

If you encounter errors or issues while sending email to your clients or configuring your mail provider, see the sections below to start troubleshooting and resolve the issue.

You can begin the troubleshooting process for many SMTP-related issues by enabling SMTP Debug for your mail provider in the Mail tab at Configuration () > System Settings > General Settings. This setting

You can also enable SMTP debugging by adding $smtp_debug = true to your configuration.php.

For more information about email features in WHMCS, see Email and Mail Providers.

General Email Issues

You may encounter the following common issues:

Error or Issue	Explanation	Next Steps
Administrators receive an email with two `To` email headers, one of which is to `undisclosed-recipients`.	The email is addressed to the same admin email address in both the `To` and `BCC` fields.	Undisclosed Recipients
External systems are flagging your WHMCS installation’s emails as spam or rejecting them.	This is usually due to the server configuration.	Email Flagged as Spam
The system isn’t sending support ticket notification emails.	This issue is usually due to a misconfiguration.	Unsent Ticket Notifications
The system is not sending product welcome emails.	This is usually due to a problem with account creation, or you may not have configured a welcome email.	Unsent Welcome Emails
The system is not successfully sending general emails, like client sign-up or order confirmations.	This issue is usually due to a misconfiguration.	Unsent General Emails
You see a syntax error when troubleshooting email-related issues.	Syntax errors are usually due to invalid code in the email template.	Email Template Syntax Errors
`Call to undefined function PHPMailer\PHPMailer\escapeshellarg()`	Your system is missing the `escapeshellarg` PHP extension.	Undefined PHPMailer Function Errors
`Connection unsuccessful. Please close this window and try again.`	The Application (client) ID and Client Secret combination for your Microsoft Entra® ID (formerly Microsoft Azure®) app are invalid.	Microsoft Connection Unsuccessful
`Could Not Authenticate`	The mail server is rejecting the SMTP details that you entered for your mail provider.	SMTP Authentication Errors
`Could not connect to SMTP host` or `SMTP connect() failed.`	SMTP Connection Errors
`Could not instantiate mail function`	You have selected PHP Mail as your Mail Provider setting.	Could Not Instantiate Errors
`Data Not Accepted`	The mail server rejected email. This can occur for many reasons.	Data Not Accepted Errors
`Email sending aborted.`	This error indicates that an unknown issue has prevented the email from sending. This commonly occurs when there is a configuration issue with the file paths at Configuration () > System Settings > Storage Settings.	Sending Aborted Errors
`Email Send Aborted By Hook`	This error indicates that a custom hook has prevented the email from sending.	Sending Aborted By Hook
`Email sending aborted by configuration`	This error indicates that you have set Disable Email Sending to ON.	Sending Aborted Configuration
`Error: the single id was not found in response`	When WHMCS attempted to import the message, it did not exist in the mailbox.	Single ID Errors
`Failed to Create $app_name application. Error detail URL may not contain a query string.`	Microsoft Entra apps do not support the redirect URI format in WHMCS.	Microsoft Mail Query Errors
`Message Body Empty`	A syntax error occurred, preventing the email from sending.	Message Body Empty Errors
`No recipients provided for message`	The client has opted out of receiving this type of email in their Email Notification preferences.	No Recipients Errors
`Sender Verify Failed`	This error indicates that the sending email address is invalid or does not exist on the SMTP server.	Sender Verify Failed Errors
`Sending Failed. Please see documentation.`	The API command cannot send the specified email template type for the `messagename` parameter.	SendEmail Sending Failure
`The following recipients failed`	This error is often due to a misaddressed email.	Failed Recipients
`TypeError: array_search(): Argument #2 ($haystack) must be of type array`	An invalid value in the Email Marketer rule (a missing billing cycle) causes an error in PHP 8.1 environments only.	Could Not Instantiate Errors

Email Piping and Importing

For issues with email piping, email importing, or other support-related email, see Troubleshooting the Support System.

Renewal Notices and Payment Reminders

You may encounter the following common issues:

Error or Issue	Explanation	Next Steps
The domain renewal link in domain renewal reminder emails is broken.	In some PHP server configurations, the system generates the URL for the domain renewal link in domain renewal reminder emails incorrectly.	Broken Renewal Links in Emails
The system sent two copies of the same renewal notice or payment overdue reminder email.	This issue may be due to the system cron running twice at the same time.	Duplicate Invoices

Last modified: October 30, 2024